Iran’s newest Fateh submarine and Sahand destroyer have joined a massive three-day military exercise in the Gulf of Oman, codenamed ‘Velayat 97’.

The vessels will patrol an area of two million square kilometers, from the Strait of Hormuz to the Gulf of Oman, and across the northern Indian Ocean. The submarines will launch missiles, and will be accompanied by helicopters as well as patrol, reconnaissance and bomber drones, Tasnim News Agency reported.

Tehran’s flexing of its military muscle also comes at a period of increased tension between the Islamic Republic and Washington, after the US unilaterally withdrew from the 2015 Joint Comprehensive Plan of Action (JCPOA, or Iran Deal) last year, and reapplied biting economic sanctions in Iran.